1. Field of the invention
The present invention relates generally to the field of protective guards for medical needles, and more specifically to a spring-loaded needle which quickly and semi-automatically retracts into a protective guard assembly upon completion of use.
2. Description of the Prior Art:
The advent of Acquired Immune Deficiency Syndrome (AIDS) has drawn attention to and substantially increased the dangers of being stuck by medical needles. It is recognized that even a minute transfer of body fluid from a person infected with a disease such as AIDS into another person's bloodstream can transmit the disease. The danger is not confined to the medical community. Increasing quantities of illegally dumped medical waste, including countless used hypodermic needles, have recently washed up on public beaches. Recognition of these dangers has lead to the development of a variety of devices for permanently shielding the tips of used medical needles.
One such device is disclosed in Magre et. al., U.S. Pat. No. 4,935,012, issued on June 19, 1990. Magre teaches a protective sheath which slides to three positions on an extended needle support hub. The sheath has a close-fitting needle exit port at the remote end of the sheath extending through an interior, conical protrusion. The initial sheath position encloses the needle point within the exit port and thus shields it against accidental contact. The second position exposes the needle for use. The third position encloses the needle point within the sheath itself and misaligns the point from the exit port to prevent further point exposure. A problem with Magre is that the handler must somehow grasp the sheath to pull it over the needle point after use. Doing this with ones hands creates a danger of needle injury. Otherwise a tool is required. In the mean time, the needle point is exposed and dangerous. Another problem is that misaligning the point from the exit port does not completely assure that it will not re-emerge.
A protective sheath device separate from the needle structure is recited in Barasch, U.S. Pat. No. 4,928,824, issued on May 29, 1990. The sheath itself is simply a tube for enclosing the needle. The needle hub snugly fits into the sheath entry port after the needle is inserted in the sheath. One embodiment shows a radial guard surrounding the sheath for shielding the handler from the point during needle insertion. Another embodiment provides a wide, coaxial outer tube for positioning the handler's fingers away from the sheath entry port. Once again, despite the radial guard or outer tube, the handler must grasp the sheath device while inserting the exposed point. If done enough times, and particularly under rushed and stressful conditions, a significant risk of accidental needle injury is presented. And, in the interval between use and insertion into the sheath, the needle point remains dangerously exposed.
Paris, U.S. Pat. No. 4,911,693, issued on Mar. 27, 1990, is essentially a variation of Magre. A telescoping spring-loaded sleeve for enclosing a needle has three positions. The first releasably locks the sleeve to enclose the point. The second leaves the point enclosed but permits sleeve telescoping against spring resistance. This position permits the needle to enter the patient while the sleeve presses against the surrounding skin. The third position again encloses the needle point, but tabs between inner and outer sleeve sections permanently lock the sleeve to prevent further telescoping and point exposure. A problem is that the handler must grasp the sleeve section nearest the point to lock it. Simply bumping the end of the sleeve prior to locking can cause the point to protrude and injure.
A tool for withdrawing a needle from a patient directly into a sheath is provided in Hogan, U.S. Pat. No. 4,842,586, issued on June 27, 1989. This tool has a cradle, a cradle stem and a tubular sheath which slides over the cradle and stem. The cradle receives the hub. Then the sheath is held against the skin while the stem is pulled outward. This action draws the needle into the sheath. Spring-loaded tabs lock the stem in the withdrawn position. The invention is intended primarily for withdrawing spinal needles, although is described as applicable to other needle types. A problem with Hogan is that the syringe or IV tube attached to the needle must be removed independently of the needle. This is particularly unpleasant for the patient receiving a hypodermic injection, because the needle must remain embedded while the syringe is removed and the tool positioned to engage the needle hub. In addition, contaminated body fluids can escape through the embedded needle during this procedure. This fluid could make contact with an open sore or cut on the needle handler, thus transmitting disease.
Luther, U.S. Pat. No. 4,832,696, issued on May 23, 1989, discloses a locking needle guard similar to that of Magre. A telescoping sleeve is retracted the hub of a needle. A cap, which initially covers and encloses the needle, is removed to expose the needle for use. When the injection is completed, the sleeve is held against the skin of the patient while the needle is withdrawn, so that the needle remains enclosed. When the sleeve is fully extended, it locks to prevent further telescoping and needle exposure. A catheter may be inserted in this manner by placing it over the needle so that the exposed needle point permits insertion. A problem with this arrangement is that the handler must grasp the sleeve near the needle point during withdrawal to keep the needle covered. This close proximity to the point of the used needle is inherently dangerous.
A variation of Barasch is disclosed in Sandhaus, U.S. Pat. No. 4,747, 835, issued on May 31, 1988. A sheath device for a used needle is provided having a radial guard surrounding its entry port to shield the handler from the point. A problem, once again, is that the handler must grip the sheath device while inserting the point, thus creating the potential for accidental sticking.
Finally, there is Hagen, U.S. Pat. No. 4,735,618, issued on Apr. 5, 1988. Hagen is a variation of Magre. A collapsible sheath has a narrow needle exit port. The sheath is collapsed to drive the needle through the port and expose it for use. Then the sheath is re-extended to withdraw the needle point through the port and inside the sheath. The sheath is then bent to misalign the exit port so that the needle is not re-exposed. The problems presented by the Hagen design are the same as those of Magre. One must grasp the sheath near the used needle point to re-extend it to cover the needle. During the interval between use and sheath re-extension, the dangerous, used needle point is exposed. And, again, misaligning does not completely assure that the point will not re-emerge.
It is thus an object of the present invention to provide a medical needle guard which does not require the handler to touch the guard near an exposed, used needle.
It is another object of the present invention to provide a medical needle guard which reliably locks the needle away from contact after use.
It is still another object of the present invention to provide a needle guard which is simple in design and easy to use.
It is finally an object of the present invention to provide a needle guard which withdraws the needle automatically when use is completed.